VARNAM2 is a negative polarity fluorescent voltage sensor (shows a decrease in fluorescence during voltage depolarization events). It consists of a voltage-sensitive rhodopsin sequence fused via a linker to the fluorescent mRuby3 protein. VARNAM2 was generated by mutagenesis of VARNAM, containing in addition the mutations G231I, deletion of residue 228W and deletion of residue 229R, and has improved fluorescence response to depolarizing voltages compared to VARNAM (PMID:36378956). For detailed kinetic and spectral properties and a comparison of VARNAM2 with other fluorescent voltage indicators, see PMID:36378956.